Dual fork lift attachment



July 24, 1962 1.. E. CARR ETAL DUAL FORK LIFT ATTACHMENT 2 Sheets-Sheet1 Filed Oct. 17, 1960 a 7 T r W .5 m m. 5 a [70W /r 5 z 4 W, l a a; w dB M NW/ 1 J/ :4 I n a a a; 1 2 4M w July 24, 1962 CARR ETAL 3,045,850

DUAL FORK LIFT ATTACHMENT Filed Oct. 17, 1960 2 Sheets-Sheet 2 N V ENTORS. 100/; 124

3,045,850 Patented July 24, 1962 3,045,850 DUAL F0131; LEFT ATTACHMENTLouis E. Carr, Qedarhurg, and Daniel C. Jones, Port Washington, Wis,assignors to Koehring Company, Miiwaukee, Win, a corporation ofWisconsin Filed Oct. 17, 1969, Ser. No. 63,141) Claims. ((31. 214-626)The present invention relates to material handling equipment and, inparticular, lift attachments for use with mobile power units such astrucks or other vehicles.

It is a general object of the present invention to improve the operationand increase the versatility of lift loaders of the type having anextensible mast.

Another object is to provide a lift attachment for loaders which has apair of load supporting devices to enlarge the useful range of work ofloaders of the present type.

A further object is to increase the outward and vertical reach of aplatform or fork lift device over that available with conventional masttype loaders. A related object is to increase the load handling capacityof such loaders and fork lifts.

A more detailed object of the present invention is to provide a forklift attachment having an extensible mast and a pair of forks in whichthe forks are movable through a given range independently of each otherto handle a great variety of materials. It is also an object of thepresent invention to provide a fork lift which can elevate a load for agiven distance without extending the lifting mast.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings, in which:

FlGURE 1 is a perspective of a dual fork lift attachment embodying thepresent invention which is illustrated mounted on a mobile truck, thelatter being shown in dashed outline;

P16. 2 is a side elevation of the attachment of FIG. 1 illustrating twopositions of the second or boom lift fork; and

FIG. 3 is a perspective of the attachment of FIG. 1 with the rigidcarriage and the boom fork in lowered position.

While the invention will be described in connection with a preferredembodiment, it will be understood that we do not intend to limit theinvention to that embodiment. On the contrary, it is the intention tocover all equivalents and modifications which may be included within thespirit and scope of the invention as defined by the appended claims.

Referring now to the illustrated embodiment of the invention of thedrawings, a lift attachment is there shown mounted on one end of awheeled truck 11. In general description, the attachment 10 comprises avertical mast 12 supported on the truck 11 by a transverse pivot pin 14which passes through the lower end portion of the mast 12 and has itsends supported by transversely spaced brackets 15 rigidly mounted on thetruck 11. To maintain the mast 12 in an upright position and providelimited forward and aft angular adjustment of the mast with respect tothe vertical, an hydraulic ram '16 is positioned to interconnect anupper joint on the truck 11 with a point on the mast 12 above thesupport pin 14. Lengthening the adjustment ram 16 swings the mast 12forwardly as for loading and unloading and retracting the ram 16 pullsthe upper end of the mast 12 rearwardly over the truck 11 for greaterstability in transporting the load from place to place.

The mast 12 itself may be of conventional form, having extensiblesections. The particular form of mast of the drawings comprises a seriesof three telescoping, interfitted, elongated box sections. The largestbox section 18 forms the top section, the smallest, 19, the bottomsection, and the middle sized box section 20, the intermediate sectionof the mast. An hydraulic ram means (not shown) of conventionalconstruction is employed in the illustrative attachment for raising thetop and intermediate sections to extend the mast.

Supported on the top section 18 of the mast is a carriage 22 mounted onthe forward side of the mast for vertical movement relative to the topsection. The carriage 22 comprises a pair of vertically spacedtransverse back bars or members 23, 24, rigidly interconnected by a pairof transversely spaced vertical guide brackets 26 fixed to the rear sideof the back bars 23, 24.

Maintaining the carriage 22 in position relative to the mast 12 toprevent forward and sidewise swing, as well as to guide the carriage inan up and down path parallel to the forward side of the mast arecooperating guide means on the mast and carriage. For this purpose, themast has an elongated rib 27 which provides clearance for a lift chain(not shown) and also forms an elongated guideway or track extendinglengthwise of the front side of the mast 12. The rear face of the mast12 forms guideways or tracks on either side thereof having a guide facedirected toward the rear of the attachment.

Cooperating with the tracks are front and rear rollers 23, 29 on thecarriage 22. The front carriage roller 28 is relatively short tocorrespond to the width of the front guideway or track 27 on the mastand is supported by a transverse axle pin 31 received in holes in theupper ends of a pair of transversely spaced brackets 32. The frontroller brackets 32 are of generally triangular outline and secured tothe central portion of the upper one of the transverse carriage bars 23.The two rear rollers 29 (only one shown) are positioned to engage therear side of the top section 18 of the mast 112 and are supported onpins 33 which are journaled in the upper rear corners of the verticalguide brackets 26 on the carriage 22. The guide brackets 26 are more orless triangular in outline and extend rearwardly from the carriage 22along opposite sides of the mast 12 to locate the upper rear corner ofeach bracket behind the back edge of the top section of the mast andthus support the rear rollers in position to engage the rear sides ofmast section 18.

The carriage is further supported by tension means which lifts orelevates the assembly relative to the mast upon extension of the mastsections. For this purpose a pair of roller link chains 36, one on eachside of the front guide ribs 27, are connected to the carriage assembly22 on opposite sides of the front roller support brackets 32. An outerrun of chain extends upwardly along the front of the top section 18 andis trained over transversely spaced sprockets 37 journaled at the top ofthe section 18. The sprockets are positioned such that an inner run ofthe roller chain proceeds downwardly on the inside of the top mastsection 18 behind the front wall of the section and is connected to theintermediate section 2% (not shown). The roller chain 36 has a lengthapproximately equal to the length of the top section 18 so that as thetop section and consequently the sprockets 37 move upwardly with respectto the next lower section of the mast, the outer run of chain isshortened to compensate for the increasing length of the inner run, thuslifting the carriage assembly 22 along its guides or tracks. When thetop section 18 of the mast is completely raised, the carriage 22 is alsoraised to the top of the mast 12 and, conversely, when the top section13 is completely lowered relative to the intermediate section 20, thecarriage 22 is at its lowest point on the top section.

'In carrying out the present invention, a dual lift or load 3 supportingmeans is provided to increase the versatility of the attachement. Forthis purpose a first lifting device illustrated in the form of a liftfork 39 is mounted directly on the carriage 22. This first or carriagefork 39 comprises a pair of transversely L-shaped tines 4t} positionedwith their bottom or foot portions 42 extending forwardly from the mastand carriage and their upright or leg portions '43 extending upwardly infront of the mast and carriage. The two tines 40 are interconnected andsupported on the carriage by Welding or otherwise fastening the legportions 43 to the transverse back bars 23, 24 of the carriage. in usethe tines 40 are usually placed under a pallet or similar load supportand the lift truck 11 is driven forwardly until the load rests againstthe back bars 23, 24 of the carriage. The carriage 22 is then lifted toraise the load as desired. Should it be desirable in transporting theload to tilt the mast 12 rearwardly for greater stability, the back bars23, 24 of the carriage prevent the load from sliding into the mast 12.

The second lifting device of the dual lift means of the presentinvention is adapted to rest in its lowered position immediately infront of the first portion formed by the carriage fork 3%. The secondportion in the illustrated construction also comprises a fork 45 whichis supported on an hydraulically actuated boom 46. In the illustrativeembodiment of the invention, the boom and boom fork are mounted on thecarriage to be raised and lowered thereby. To accomplish this, the liftcarriage 22 has two uprights or boom supports 47 fixed to the back bars23, 24, one upright being spaced outwardly on each side of the mast toprovide a stable base. Each of the uprights comprises a pair ofparallel, upright plates 43, 49 relatively closely spaced to each otherand having their lower forward edges rigidly fixed, as by welding, tothe rear face of the carriage back bars 23, 24. The plates 48, 49 extendupwardly and rearwardly to the rear of the back edge of the mast 12.Extending between each set of support plates 48, 49 and pivotallyconnected to the upper end portion of the plates by a transverse pivotpin 51 is the rear end of a rigid boom arm 52. As seen in FIG. 2 of thedrawings, the pivotal connection 51 permits each of the two boom arms 52to swing upwardly and downwardly for lifting and lowering the boom forkassembly 45.

The boom fork assembly 45 comprises a pair of rigid L-shaped tines 54interconnected by upper and lower back bars 55, 56 rigidly fixed to theupright legs 57 of the tines 54 at vertically spaced positions. Thebottom or foot portions 58 of the tines 54 extend forwardly from theattachment in the same direction as the foot portions 42 of the carriagefork 39. To support the boom fork 45 on the forward end of the boom 46 alug 60 and connecting pivot pin 61 are provided on the lower back bar 56for receiving and pivotally connecting the forward end of each boom arm52. Preferably, the lugs 60 are spaced transversely from each other adistance equal to the spacing between the upright boom supports 47 onthe carriage 22 for maintaining the boom arms 52 in substantiallyparallel relation. To strengthen the boom 46 against relative twistingand side sway, rigid struts 62 are interposed between the boom arms 52at spaced intervals. In the illustrated attachmeint of the drawings, twosuch struts 62 are shown connected at their ends to the respective boomarms 52.

'In order to maintain the boom fork level during swing of the boom, aleveling link in the form of a tension member or rod 64- is provided.Preferably, two such tension rods 64 are used, one above each boom arm52.

Each of the rods 64 is pivotally connected at its rear end to an upwardextension 65 on the outer one of the boom support plates 49.

The pivotal connection is made by a shackle 66 adjustably connected asby screw threads to the rear end of the rod 64, and by a pivot pin 67which passes through the shackle 66 and an aperture in the support plateextension 65. The forward end of each rod 64 is pivotally con nected tothe upper back bar 55 of the boom fork assembly by means of a transversepin 68 and rearwardly extending lugs 69 fixed to the upper back bar. Bysubstantially vertical alinement of the rear and forward pivotalconnections, respectively, of the leveling links 64 and boom arms 52, aparallelogram linkage is formed which maintains the boom fork 45substantially level as it is raised and lowered by swing of the boom 46.

In further carrying out of the invention, means are provided to givefree lift to the boom fork 45 relative to the carriage fork 39 and mast12. For this purpose, hydraulic ram means is provided to swing the boom46 about its pivotal support 51. To accomplish this, an hydraulic ram71, preferably of the double acting type, is mounted under each boom arm52 to exert an upward push on the arm at a point forwardly of itssupport pivot 51. As seen in the drawings, each ram 71 is positionedbetween a respective set of upright support plates 43, 49 having itslower or cylinder end 72 pivotally supported near the lower end of theplates at "73 and its upper or rod end 74 pivotally connected to thecorresponding boom arm 52 by a lug or shackle 75 fixed to the undersideof the arm. A transverse pin 76 having its ends received in suitableapertures in the upright plates 48, 4-9 forms the lower pivotalconnection for the ram 71 and a similar pivot pin 77 passing through theshackle 75 and end of the piston rod '74 forms the upper connection.

By actuating the hydraulic ram 71 the boom fork 45 may be raised orlowered as desired relative to the mast 12 and the carriage form 39. Tosupply pressure fluid to the boom rams '71 at all elevations of themast, a pair of hydraulic conduits or hoses 80, in the case of a doubleacting ram, are provided for each ram. To prevent tangling of the hoses80, a pulley arrangement is utilized to support and keep them straightat all elevations of the mast and carriage. Positioned on each side ofthe upper end of the top section 18 of the mast are two double groovedpulleys 81, 82 supported side by side on a transversely extending shaft83 fixed to the mast. The pair of hoses extends upwardly from suitablecouplings 84 on the truck 11 which contains the pressure fluid supply(not shown) over one of the two pulleys 81, each hose lying in one ofthe grooves. The hoses then proceed downwardly, under and around afreely suspended double grooved pulley 85, from there upwardly over thesecond of the upper double grooved pulley 82, and finally downwardly tothe hydraulic ram 71. Hoses for the other of the boom rams are trainedin like fashion over identical supported pulleys 81, $2 and under anidentical freely suspended pulley 85.

By means of the foregoing pulley arrangement for the hoses 859, thefreely suspended pulley 85 by its own weight keeps the hoses taut but isfree to move upwardly toward the supported pulleys 81, 82, playing outhose as the mast is extended, and to move downwardly to take up hose asthe mast is retracted. If desired, the free pulley 85 may be providedwith vertical guide means of any well known form to eliminate sidewiseswing of the pulley as the lift truck is moved about.

In the operation of a lift device embodying the present invention, itwill be apparent that the dual load supporting means may be usedtogether or individually, thus increasing both the capacity and range oftypes of work which can be done. For example, the boom fork 45 may beraised by means of the boom rams 71 and a load placed on the carriagefork 39. The boom fork 45 may then be lowered and a second load placedon it for simultaneously transporting and lifting two loads. For thispurpose, the pivotal connections 51 are positioned substantially abovethe carriage 22, and the boom is of sufficient length to locate the boomfork ahead of the carriage fork giving space for holding a load on thecarriage fork and at the same time actuating the boom fork 45. It isalso noted that with the present load lifting device the hydraulic rams,including the upper pivotal connections of the rams 71, are locatedbehind the carriage to free the carriage fork of any obstruction inloading it.

Also increasing the versatility of the present device is the placing ofthe boom fork not only ahead of the carriage fork, but also below thecarriage fork, when the boom is in its lowest position. Preferably, theboom fork when so positioned is slightly below the surface on which thesupporting vehicle is standing. By this arrangement, the boom fork maybe used to lift loads which are resting directly on the ground or whichare actually below the ground upon which the wheel truck 11 rests.

In addition to concurrent use of both forks to lift separate loads ofmaterials, the position of the boom and boom supporting means permitsthe boom to be used as a hold-down for large bulky loads on the carriagefork. This is accomplished by raising the boom While loading thecarriage fork and then lowering the boom until it rests on the top ofthe material underneath.

The present loader is capable of other advantageous uses, representativeof which are placing loads carried by the boom fork above the highestpoint of the mast and also forwardly of the mast such as across a trenchor through an opening too narrow for the vehicle to enter.

We claim as our invention:

1. A lift attachment for use on a vehicle having a source of pressurefluid comprising, in combination, an extensible mast having elongated,relatively slidable sections including a top section, said mast beingadapted to be mounted on said vehicle in a substantially verticalposition, a carriage, means for guiding said carriage for movementlongitudinally of said top section, means for raising said carriagerelative to said top section, a first lift fork mounted on and carriedby said carriage and extending forwardly from said mast for movementwith said carriage, a second lift fork positioned forwardly of saidfirst lift fork, a boom having its outer end portion pivotally connectedto said second load supporting means and having its inner end portionpivotally connected to said carriage at a point upwardly and rearwardlyof said first lift fork thereby permitting simultaneous loading of saidfirst and second lift fork, and hydraulic ram means positioned behindsaid first lift fork and connected at its ends to said carriage and saidboom respectively for swinging said boom and second lift fork upwardlyrelative to said carriage to raise said second lift fork upwardly andforwardly of the top of said top mast section.

2. A lift attachment for use on a vehicle having a source of pressurefluid comprising, in combination, an extensible mast adapted to bemounted on said vehicle in a substantially vertical position and havingelongated, telescoping sections including a top section overfitting thenext lower section, a carriage having a pair of transverse verticallyspaced bars and a pair of vertical plates rigidly interconnecting saidbars and extending rearwardly along the sides of said top section of themast, a front roller mounted centrally of said upper transverse bar andrear rollers mounted on the rear end portions for said vertical platesfor engaging the front and back sides respectively of said top sectionfor guiding said carriage for movement longitudinally of said topsection, chain means connected to said carriage for raising saidcarriage relative to said top section upon extending said top sectionrelative to the next preceding mast section, a first lift fork carriedby said carriage and extending forwardly from said mast for unisonmovement with said carriage, a second lift fork for positioning thelatter forwardly and below said first lift fork, a boom having its innerend portion pivotally connected to said carriage at a point upwardly andrearwardly of said first lift fork for vertical swing and having itsouter end portion connected to said second lift fork for positioningsaid second lift fork forwardly and below said first lift fork when saidbottom is in lowered position, and hydraulic ram means interconnectedbetween said carriage and said boom for swinging said boom and secondlift fork upwardly relatively to said carriage to raise said second liftfork above and forwardly of said top mast section when the said carriageis in raised position.

3. A lift attachment for use on a vehicle having a source of pressurefluid comprising, in combination, a mast having elongated, telescopingsections of relatively slidable interfitting box shape and including atop section overfitting the next lower section, said mast being adaptedto be mounted on said vehicle in a substantially vertical position, acarriage having front and rear rollers positioned to engage the frontand back sides respectively of said top section for guiding saidcarriage for movement longitudinally of said top section, meansconnected to said carriage for raising said carriage relative to saidtop section upon extending said top section relative to the nextpreceding mast section, a first load supporting means carried by saidcarriage and extending forwardly from said mast for unison movement withsaid carriage, a second load supporting means positioned forwardly ofsaid first load supporting means, a boom having its outer end portionpivotally connected to said second load supporting means and having itsinner end portion pivotally connected to said carriage at a pointupwardly and rearwardly of said first load supporting means, andhydraulic ram means interconnected between said carriage and said boomat a point on said boom outwardly of said inner end portion for swingingsaid boom and second load supporting means upwardly relative to saidcarriage to permit loading of said first load supporting means and forraising said second load supporting means above and forwardly of the topof said top mast section.

4. A load lifting attachment for use on a vehicle having a source ofpressure fluid comprising, in combination, a mast adapted to be mountedon said vehicle in a substantially vertical position, and having aplurality of relatively movable sections including a top section forextending and retracting said mast, a carriage on the forward side ofsaid top section, means for moving said carriage up and down along saidtop sect-ion, a first lift fork carried by said carriage, a verticalsupport bracket positioned on opposite sides of said mast, each of saidsupport brackets including a pair of vertical, transversely spacedsupport plates having the lower forward side thereof fixedly connectedto said carriage for unison movement therewith, said support plateshaving an upper end portion projecting upwardly and rearwardly of saidcarriage, a boom assembly including a pair of transversely spaced armshaving their inner end portions extending between, and pivotallyconnected to, the upper end portions of respective pairs of said supportplates for vertical swinging movement of said boom, a second lift forkpivotally supported on the outer ends of said arms, said boom armsextending forwardly and downwardly in the lowered position of said boomto position said second lift fork forwardly and below said first liftfork, an hydraulic ram positioned between each pair of the supportplates and having its end portions pivotally connected to the supportplates and corresponding boom arm respectively for raising and loweringsaid lift fork relative to said carriage and said mast, and levelingmeans including a tension member interconnecting an upper portion ofsaid second lift fork and an, upper extension on said support bracketfor maintaining said second lift fork substantially horizontal uponswinging of said boom.

5. A load lifting attachment for use on a vehicle having a source ofpressure fluid comprising, in combination, a mast adapted to be mountedon said vehicle in a substantially vertical position and having aplurality of relatively movable sections including a top section forincreasing and decreasing the length of said mast, a carriage on theforward side of said mast having a pair of tranrsverse vertically spacedbars and a pair of vertical transversely spaced plates interconnectingsaid bars, first and second vertical support brackets positioned onopposite sides of said mast, each of said support brackets including apair of vertical, transversely spaced support plates having theirforward sides fixedly connected to the carriage bars for unison movementwith said carriage, said support plates having an upper end portionprojecting upwardly and rearwardly of said carriage, a boom assemblyincluding two transversely spaced boom arms, each of said arms havingits inner end portion positioned between the upper end portions of acorresponding pair of said support plates and pivotally connectedthereto for vertical swinging movement of said boom, a lift forkpivotally supported on the outer ends of said arms, a pair of hydraulicrams positioned respectively between said pairs of support plates, eachof said rams having its lower end portion pivotally supported by saidsupport plates and its upper end portion connected to the correspondingboom arm for raising and lowering said lift fork relative to saidcarriage and said mast, and a tension member pivotally connected at itsend portion between an upper portion of said lift fork and an upperextension on said support bracket for maintaining said forksubstantially horizontal upon swinging 'of said boom.

References Cited in the file of this patent UNITED STATES PATENTS

